spi: hisi-kunpeng: Add verification for the max_frequency provided by the firmware

If the value of max_speed_hz is 0, it may cause a division by zero
error in hisi_calc_effective_speed().
The value of max_speed_hz is provided by firmware.
Firmware is generally considered as a trusted domain. However, as
division by zero errors can cause system failure, for defense measure,
the value of max_speed is validated here. So 0 is regarded as invalid
and an error code is returned.

Signed-off-by: Devyn Liu <[email protected]>
Reviewed-by: Jay Fang <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Mark Brown <[email protected]>

Author: Devyn Liu

drivers/spi/spi-hisi-kunpeng.c

@@ -481,6 +481,9 @@ static int hisi_spi_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
+	if (host->max_speed_hz == 0)
+		return dev_err_probe(dev, -EINVAL, "spi-max-frequency can't be 0\n");
+
 	ret = device_property_read_u16(dev, "num-cs",
 					&host->num_chipselect);
 	if (ret)